A method for managing metadata in a scale out storage system is disclosed. The system includes a plurality of nodes, a storage pool, first metadata that maps logical addresses of logical data blocks to corresponding content identifiers, and second metadata that maps content identifiers to corresponding physical addresses of physical data blocks in the storage pool and maintains a reference count. During an add-a-node operation, the processors are configured to move from the existing nodes to the new node some of its physical data blocks, their content identifiers and reference counts in the second metadata without accessing or altering the first metadata. A method is disclosed to move a logical device from one node to another by de-activating the logical device's first metadata on the first node and activating and retrieving the logical device's first metadata on the second node.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method implemented in a data storage system of moving data and logical devices, said method comprising: storing data blocks in a data storage pool comprising a plurality of data storage devices distributed among two or more data storage nodes, each data block associated with a unique content identifier; storing metadata mapping the logical addresses of logical data blocks associated with one or more logical devices to physical addresses of corresponding data blocks stored in said data storage pool, said metadata comprising: first metadata mapping the logical addresses associated with said logical devices to corresponding content identifiers; and second metadata mapping the content identifiers to corresponding ones of the physical addresses of the data blocks; moving an access point for a first logical device from a first one of said data storage nodes to a second one of said data storage node.
2. The method of claim 1 wherein moving the access point comprises: disabling access to said logical device on the first data storage node; and enabling access to said logical device on the second data storage node.
3. The method of claim 1 wherein moving the access point comprises: detecting a failure of the first data storage node; and enabling access to said logical device on the second data storage node responsive to detection of the failure.
4. The method of claim 1 further comprising organizing the first metadata associated with the first logical device in a tree data structure comprising a root and a plurality of entries associated with logical addresses on the first logical device.
5. The method of claim 4 wherein moving the access point comprises: retrieving, by the second data storage node, the root of the tree data structure associated with the first logical device; and activating access to said logical device on the second data storage node.
6. The method of claim 5 wherein moving the access point further comprises retrieving the entries associated with the logical addresses of the first logical device when the logical addresses are accessed.
7. The method of claim 1 wherein moving the access point further comprises pushing the first data storage node's local cache for the first logical device to the second data storage node.
8. A data storage system comprising: a plurality of data storage nodes connected by a network; a data storage pool comprising a plurality of data storage devices distributed among the data storage nodes, and processing circuitry distributed among the data storage nodes, said processing circuitry configured to: store data blocks in said data storage pool, each data block associated with a unique content identifier store, in said data storage pool, metadata mapping the logical addresses of logical data blocks associated with one or more logical devices to physical addresses of corresponding data blocks stored in said data storage device, said metadata comprising: first metadata mapping the logical addresses of logical data blocks on said logical devices to corresponding content identifiers; and second metadata mapping the content identifiers to corresponding ones of the physical addresses of the data blocks; and move an access point for a first logical device from a first one of said data storage nodes to a second one of said data storage node.
9. The data storage system of claim 8 wherein, to move the access point, the processing circuitry is configured to: disable access to said logical device on the first data storage node; and enable access to said logical device on the second data storage node.
10. The data storage system of claim 8 wherein, to move the access point, the processing circuitry is configured to: detect a failure of the first data storage node; and enable access to said logical device on the second data storage node responsive to detection of the failure.
11. The data storage system of claim 8 wherein the processing circuitry is further configured to organize the first metadata associated with the first logical device in a tree data structure comprising a root and a plurality of entries associated with logical addresses on the first logical device.
12. The data storage system of claim 11 wherein, to move the access point, the processing circuitry comprises: a processor in the second data storage node configured to retrieve the root of the tree data structure associated with the first logical device and enable access to said logical device on the second data storage node.
13. The data storage system of claim 12 wherein, to move the access point, the processing circuitry in the second data storage node is further configured to retrieve the entries associated with the logical addresses of the first logical device when the logical addresses are accessed.
14. The data storage system of claim 8 wherein, to move the access point, the processing circuitry in the first data storage node is further configured to push its local cache for the first logical device to the second data storage node.
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May 3, 2019
March 2, 2021
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